英语外教一对一培训机构哪家好?首选，先把英语口语培训授课模式介绍一下：

外教小班：外教小班属于比较传统的授课模式了，一般老师说得多，对话少，同学的口语水平也不一，课程难度难以符合个人水平。在去培训机构路上花费的时间成本就更不用说了。

视频授课：视频授课利用已录制好的口语视频学习，这种授课模式虽是收费最低的，但只看不练，自己练口语无人监督，无法交流沟通，根本达不到提高口语的能力。

电话授课：电话授课是近几年流行起来的新兴授课模式，利用电话或网络电话作为教学手段来对学员进行英语培训。电话授课是最直接的外教一对一口语对练，妈妈再也不用担心我找不到真正外教一对一培训了~~

这段时间，小编在收集大量学员评价时，反馈电话授课的学习效果最好！

根据调查，这里给大家推荐新东方的电话英语口语培训，全程外教一对一陪练。现在还有免费的外教一对一口语测评，想知道电话授课的感觉就去体验一下吧！

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新东方电话授课介绍：点击查看详情>>

Essential and Nonessential Adjective Clauses

必要定于从句和不必要定语从句

Remember that an adjective clause is a dependent clause that acts like an adjective in the sentence. This means that it gives more information about a noun or pronoun in the sentence.

定语从句是一个从属分句，在句中作形容词。可以给出更多关于句中名词或代词的信息。

Sometimes the information given by the adjective clause is essential. An essential adjective clause is one that is needed for the sentence to make sense. If you took it out, you would not know all the information that you need to know.

有时，定于从句提供的信息至关重要。句中需要这一从句使句子的意思更完整。如果缺少此从句，就了解不到完整的信息。

At other times, the information given by the adjective clause is nonessential. A nonessential adjective clause is one that is not necessary. The sentence still makes sense and you know everything you need to know even without the clause. So, you could take it out.

有些时候，定语从句提供的信息不是那么重要。没有这一从句，句子也有意义，而且意思完整。因此可以删掉这一从句。

When a sentence has a nonessential adjective clause, the clause is set apart with commas. This shows that it is not essential.

如果一句中有不必要定语从句，就会用逗号把从句隔开，表示这句话并不是必须的。

Examples of Essential and Nonessential Adjective Clauses:

必要定语从句和不必要定语从句的例子：

Examples of essential adjective clauses:

必要定于从句的例子：

1) The man who left his wallet is coming back for it.

1)丢了钱包的男人又回来找钱包了。

It is essential for us to know which man.

有必要知道是哪个男人。

2) I do not remember the day that my cousin was born.

2)我不记得表弟是哪天出生了。

It is essential for us to know which man.

有必要知道是哪一天。

3) The time when I go to bed changes in the summer.

3)夏天的时候，我上床的时间跟其他季节不同。

It is essential for us to know what time.

需要知道什么时间。

4) I want the dog that is black and white.

4)我想要那只黑白相间的狗狗。

It is essential for us to know which dog.

我们需要知道是哪只狗。

5) Could you bring me the cup that is on the table?

5)可以拿给我桌上的杯子吗?

It is essential for us to know which cup.

我们需要知道是哪个杯子。

Examples of nonessential adjective clauses:

不必要定语从句的例子：

1) Lisa, who takes ballet with Jan, is my best friend.

1)和简一起跳芭蕾舞的丽萨是我最好的朋友。

It is not essential for us to know about the ballet.

不需要知道更多关于芭蕾舞的信息。

2) I won first prize, which was a blue ribbon.

2)我获得了一等奖，是条蓝色的丝带。

It is not essential for us to know the type of prize.

我们不需要知道是什么类型的奖。

3) My grandfather, who lives on a farm, said he would teach me to ride a horse.

3)我的祖父住在农场，说要教我骑马。

It is not essential for us to know where he lives.

我们不需要知道他住在哪。

4) The school library, which is next to the cafeteria, is my favorite place in the school!

4)咖啡馆旁边的图书馆是我最喜欢的地方。

It is not essential to know that it is next to the cafeteria.

我们不需要知道图书馆在咖啡馆旁边。

5) Mary, whose mom is a nurse, sits behind me in class.

5)妈妈是护士的玛丽，上课时坐在我旁边。

It is not essential for us to know what Mary's mom does.

没有必要知道玛丽的妈妈做什么。